To: "John H." 
Subject: Re: due to some kind of interference, monitor display is "shaking"
References: 
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"John H."  writes:

> ok, the thing i bought from radioshack is
> 75-ohm tv/vcr/fm interference filter
> ????


You mean this product
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=15-579

Eht web page says:
"Cuts CB/Ham interference. This 54-900MHz high-pass filter installs 
inline at the 75-ohm (F connector) input jack on TV or VCR."

According the documentation this device is designed to be 
a high-pass filter. This kind of high pass filter if the 
filtering is all this does is not do what is wanted. 
We want to cut the current flowing on the cable shield with 
an antenna cable isolator without too much affecting the 
signal inside cable. 
This radioshack device is according to the documentation 
designed to affect the signal inside cable (high pass filter it) 
and does not tell anything what it does with the shield currents 
(propably does not do anything). 

If you have a multimeter measure with ohms range if there is an 
electricl connection between the input and output connector. 
If you measure low resistance (few ohms or less), then it is 
sure that this kind of filter does not do anythign to ground loop 
problem! If you measure practically infinite resistance between 
the inout and output connector shields, then this device is 
type of isolator we want.


I have used successfully the following pretty similar looking 
(propably made by same manufacturer) device that ise designed 
as antenna isolator to solve ground loop problems.

Jebsee EU-634 
http://www.vekoy.com/product_info.php?manufacturers_id=84&products_id=3568&osCsid=15511701308b91c625771bceaea1c0bd

-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/